Speed responsive coupling



April17, 1951 PURDY V 7 2,549,748

SPEED RESPONSIVE COUPLING Filed May 7, 1945 INVENTOR t a a. flmw ATTO R N EY Patented Apr. 17,1951

Rolland M. Purdy,

Bendix Aviation Corp Bainbridge, N. Y., assignor to oration, New York, N. Y.,

a corporation of Delaware Application May 7, 1945, Serial No. 592,387

This invention relates to, couplings, and more particularly to means for connecting two rotating parts so that automatic, angular adjustments of said parts may be effected during rotation there- Among the many uses of this invention is its particular application to the timin of sparks produced bytheignition system of an internal .combustion engine and the invention will be particularly described in connectionwith a mechanism suited to that particular use, but it is to be understood that this particular description is for purposes of illustration only and does not constitute a limitation within the natural scope of the invention.

adapted to automatically advance the spark of an internal combustion engine when a particular speed of rotation is reached and to automatically retard the spark when a difierent increased speed of rotation is reached.

Another object of the invention is to couple driving and driven shafts by a novel coupling that automatically changes the angular relation of the driving and driven shafts at particular speeds of rotation.

Another object is to provide a novel speed sensitive coupling between rotating parts, the sensitivity of which can be varied to make it operate at different speeds.

Another object is to provide novel means to control the movement of a centrifugal weight, and a further object is to obtain such control by changing the leverage of a controlling device on the weight.

A particular object of the invention is to provide novel means for simultaneously and equally adjusting a plurality of centrifugal weights.

The above and further objects and novel features of the invention will more fully appear from the followin detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only, and are not intended as a definition of the limits of the invention, reference for this latter purpose being had primarily to the appended claims.

In the drawings, wherein like reference, characters refer to like parts throughout the several views,

Fig. 1 is a vertical section on the line l-l of Fig. 2, looking in the direction of the arrows;

-Fig. 2 is a vertical section on the line 22 of 14 Claims. (Cl. 64-25) Fig. 1, looking in the direction of the arrows, the cover plate having been removed to expose the flyweights;

Fig. 3 is a vertical section on the line 3-3 of Fig. 1, looking in the direction of the arrows, the cover plate havin been removed to expose the flyweights; and,

Fig. 4a is an end view of a heavy flyweight and Fig. 4b is an end view of a light flyweight, the weights being arranged to show a size relationship that may sometimes be employed.

Internal combustion engines are desirably operated at certain speeds with an advanced spark and at other speeds with a retarded spark. In the case of automobile engines the advance and retarding of the spark were originally accomplished by manual means, but more recently by automatic means. In aircraft engines it is also desirable upon certain occasions to operate with an advanced and on other occasions with a retarded spark. a 1

This invention provides the ignition systems of such engines with novel speed sensitive mechanism that automatically advances 0r retards the spark when selected engine speeds have been reached, and contemplates novel means for altering the angular relation of driving and driven rotating members. In the drawings, the drive shaft of a magneto, timer, distributor or the like of an ignition system is indicated by the numeral l0. Upon this drive shaft there is a driving gear H, a driven gear I2, and'a rotary support l3 between them. Double ended bearing pins I4 are mounted in the support and carry gear segments I5 that are in mesh with the gear II and gear segments l6 that are in mesh with the gear 12. The gear segments l5 extend beyond the points of pivotal attachment to the pins l4 and form oppositely disposed flyweights II that are of relatively heavy construction. Gear segments l6 extend beyond the pins to which they are pivoted as flyweights 18 which, in the mechanism illustrated, are of relatively light construction as shown in Fig. 4. Annular cover plates 35 and 35 are mounted onthe pins M by bolts 3'! and serve to retain the flyweights on the pins.

The engine drive (not shown) meshes with the splines 19 of the gear II and rotates the latter; the rotative effort of the gear I l against the gear segments I5 urges the flyweights ll centripetally and forms in effect a positive driving connection that rotates the pins I4. the support I 3, the gear segments I6, the gear I2 and the shaft In as a unit. However, when the speed ofrotation has "increased sufficiently the flyweights I! move centrifugally under the impulse of centrifugal force, the gear Segment I5 walks about the gear I I advancing the support I3 and all the mechanical connections that follow it, and imparting an angular advance to the driven gear I2, and to the circuit breaker cam or other mechanical device operated thereby. As the speed of rotation increases still further, the fiyweights I8 are actuated to apply through gear segments I6 and gear I2, a retrograde motion whereby reverse adjustment of gear I2 and shaft I!) with respect to gear II will take place and the spark will be retarded. It will be understood that this relative angular adjustment can be availed of in either direction with this coupling, depending upon which is the driving and which is the driven ear.

Referring now to the novel construction of the embodiment of the invention that is set forth in the drawings, It indicates generally a drive shaft,

of an instrument such as a magneto or ignition timer, having an abutment formed on the shaft as a thrust bearing for the inner race of a ball bearing 2| that carries the bearing area 22 of the shaft I9. Outwardly of the said abutment and bearin area the shaft I 0 is provided with splined portion 23 and a reduced smooth portion 24 that is screw threaded at its end for the reception of a nut 25.

The gear I2 is mounted on Shaft II) by interfitting internal splines that fit the splines 23 and is provided with external gear teeth adapted to mesh with gear segments I 6. A washer 2! fits over the portion 24 of the shaft III and is brought up against a shoulder formed inside the gear I2. A bearing and spacing sleeve 28 is placed over the end 24 of the shaft and brought up against the washer 2? and the hub 29 of the annular support I3 is mounted upon the inner end of the sleeve so that a portion of the hub fits within the end of gear I2 and bears against washer 21. The gear Ii is mounted on the sleeve 28 with an inner annular flange circumscribing the hub 29. The parts of the mechanism just described are held in assembled relation by means of a thrust washer 30, a

lock washer and the nut 25. v 'Ihe central portions 31 of pins I4 are larger than the bearing portions at the ends thereof and are mounted fixedly on a single diameter of the support I3 in order that the parts of the apparatus may be in dynamic balance. The enlarged central portions SI of the pins l4 project slightly beyond the faces of the support and constitute abutments that, together with the sleeve 28, give clearance to the parts of the assembly. The gear segments I5, I6 are spaced from the support I3 by the projecting parts 3| of the pins; the gears I2 and II are provided with clearance by the hub 29, which bears against the washer 2'! and is of sufficient extent to provide clearance between the face of the support 33 and the gear segment I 6 and the sleeve 28 provides clearance between the ends of gear I I, washer and support I3.

Because of their inter-fitting splines, the gear I2 must rotate with the shaft I0, and because of the connection of the gears I2 and II with the support I3, the parts of the mechanisms will rotate as a unit despite the revolvable mounting of gear II and support I3 on the sleeve 28.

In order that the operation of the flyweights may be controlled, novel means are provided whereby they may be made to act at selected speeds of rotation. In the preferred form these ditions of higher engine speeds.

novel means provide for the application to the flyweights of equal maximum controlling force to set the speeds at which they operate and for adjustment by applying that force to the flyweights with different leverage. This novel controlling means also contemplates equal and simultaneous adjustment of each pair of weights.

Mounted at the circumference of the support I3 are adjustable abutment rings 40 and 4 I, having leaf springs 42 riveted thereto and bearing upon the outer surface of the flyweights so as to load them centripetally and hold them in a position in which the abutments 43 of each pair of the fiyweights make contact with flat areas on the gear segments. The outer surfaces of the flyweights have portions that are preferably concentric with the abutment rings when in the centrifugally energized position, so that the maximum pressure of the springs 42 on the surfaces of such fiyweights is always the same regardless of the position of the ring. Novel adjustability is obtained in this preferred structure by a change in leverage secured by moving the abutment ring with respect to the flyweights so that the springs travel over the surface thereof, the leverage of the spring being equal in each such position to the distance between the point at which it touches the flyweight surface and the center of the supporting pin I4. Each ring 40, 4| is made adjustable by a pair of mounting slots 44 in the mounting flange 46 thereof. The adjustability of each spring is determined by the length of its mounting slots. Mounting bolts 4'! pass through each slot into seats in the support I3 and may be screwed down against lock washers and the mounting flange to hold the ring in adjusted position. A similar and separate mounting is provided for each ring. It will be understood, therefore, that the speeds at which the operation of the driving and driven members takes place is governed in part by the relative Weight of the flyweights and in part by the leverage of the springs. By means of these two elements of control, the very widest selection of operating conditions can be secured.

Assuming now that power is being applied to the driving member II, simultaneous and equal rotation of all parts will occur at speeds below those at which the heavy flyweights I! are thrown outward by centrifugal force. As generally employed .in the timing of aircraft magnetos, the heavy flyweights act instantaneously and completely at a selected speed to give the pins 3I, the support I3, the gear I2, the shaft ID and the mechanism driven by it an abrupt and complete advance. Thereafter, as long as the speed of the engine is below that at which the lighter flywei'ghts I8 become operative, the selected advanced setting of the magneto will be maintained. Under certain circumstances it is desirable to have a retarded spark under con- I Therefore, the lighter flyweights may be of such weight and so controlled by the springs as to operate under the influence of centrifugal force to produce the desired retarding of the spark at the selected advanced speed. When that speed is reached, the lighter fiyweights I8 turn the gear I2 in a direction opposite to thatproducecl by the heavy flyweights, and the retarded position of the parts I2 and ID will be maintained so long as such high engine speeds are-in use.

In slowing downthe engine from high speeds, a reverse series of operations occurs, the light the shaft l0.

fiyweights being thrown centripetally at the higher critical speed by the'springs which bear upon them, advancing the driven gear [2 and As the engine slows to the critical lowerspeed, the heavy flyweights are returned centripetally and the parts l3, l2 and ID are again retarded. 1

There is thus provided novel coupling means for driving and driven members that is accurate.- ly responsive to speeds of rotation, that is adjustable so that automatic control will take efiect at those speeds that are selected, and that is of such simple construction that it can be made by ordinary methods of manufacture. The apparatus is self-contained, self-operated,'and.;re.-

quires a minimum of attention. It is adapted for use in manysituations where automatic and limited change of the angular relation of. driving and driven members is to be accomplished by speed responsive means.

Certain modifications may be made in the foregoing structure; for instance, the curvedsurfaces of the flyweights may be shaped to produce alterations in the effect of .the springs, being so shaped in one instance to produce increasing spring pressure as spring leverage is increased, and in another case producing decreasing spring pressure. The flyweights may be changed at will to others of different weight to obtain changes in ope-rating speeds. ment rings having springs of different construction or strengths may be made available to alter the operating characteristics of the device.

Although only one embodiment of the in: vention is illustrated and described in detail, it is to be expressly understood that the same is not limited thereto. As will now .be apparentito those skilled in the art, various changes, such as in the design and arrangement of the parts illustrated, may be made in the illustrated embodiment of the invention without departing from the spirit and scope of the invention. For a definition of the limits of the invention, referenceis had primarly to the appended claims.

What is claimed is:

1. Speed sensitive mechanism of the class described comprising a rotatable support, a flyweight pivotally mountedon said support having meansto turn a gear by motion centrifugally imparted, means to limit the centrifugally imparted motion of said flyweight comprising a circumscribing abutment ring, approximately concentric surfaces on said ring and said flyweight, spring means carried by said ring and bearing on said fiyweight, and means providing for movement of the ring with respect to the fiyweight to vary the point of application of the pressure of the spring means thereto.

2. A speed sensitive coupling for rotatable members comprising a rotatable support, a plurality of fiyweights pivoted to said support, spring means for applying pressure to said flyweights to oppose the centrifugal motion thereof, and means comprising an annular member carrying said spring means and mounted on the said support for adjustment in a arcuate path concentric with the axis of said support for simultaneously and equally adjusting the said spring means with respect to each of said flyweights.

3. Speed sensitive mechanism of the class described comprising a rotatable support, flyweights pivotally mounted on said support having means to turn a gear by motion centrifugally Substitute abutimparted, means to limit the centrifugal'ly im parted motion of said flyweights comprising a circumscribing abutment ring engageable by said flyweights and mounted on said support for adjustment relative thereto in an arcuate path, concentric surfaces on said ring and said flyweights, and spring means carried by said ring and adjustable therewith to bear on different parts of said concentric fiyweight surfaces.

4. Speed sensitive mechanism of the class de.-. scribed comprising driving and driven members, a rotatable support angularly movable relative to both said members, fiyweights pivotally mounted on said support having gearisegments engaged with said driving and driven members,

said fiyweights being loaded by springs mounted for movement independently of and bodily with respect to said fiyweights to vary the leverage thereon for operation by centrifugal force at dif-' ferent speeds.

5. A speed sensitive coupling comprising a driving member, a driven member, a rotary support between said members, flyweights pivotally mounted in pairs on each side of said support having gear segments in mesh with said driving and driven members, respectively, and adjustable spring pressure applying means to apply spring pressure simultaneously to the flyweights of each pair at selected corresponding points thereon to oppose contrifugal motion thereof.

'6. A speed sensitive coupling comprising a driving gear, a driven gear, a rotary support between said gears, fiyweights pivotally mounted in pairs on each side of said support having gear segments in mesh with said gears, means to apply spring pressure to the fiyweights to oppose centrifugal motion thereof, and means to change the points of application of said spring pressure to the flyweights whereby the centrifugal motion thereof may be opposed with selected leverage.

'7. A speed sensitive mechanical drive comprising a driving gear, a driven gear, a rotatable support between said gears, flyweights pivotally mounted on the support having gear'segments in engagement with said driving gear, flyweights pivotally mounted on the support having gear segments in engagement with said driven gear, spring means to oppose the outward motion of the flyweights, and means to vary the leverage of said spring means on said flyweights.

8. A speed sensitive mechanical drive comprising a driving gear, a driven gear, a rotatable support between said gears, fiyweights pivotally mounted on the support having gear segments in engagement with said driving gear, means to limit the centripetal motion of the said flyweights, fiyweights pivotally mounted on said support having gear segments in engagement with said driven gear, means to limit the centripetal motion of the said flyweights, abutment rings adjustably mounted on said support to limit the centrifugal motion of the fiyweights, and spring means attached to said rings bearing upon said flyweights to oppose the centrifugal motion thereof.

9. A speed sensitive mechanical drive comprismg a driving gear, a driven gear, a rotatable support between said gears, flyweights pivotally mounted on the support having gear segments in engagement with said driving gear and having mutually co-acting abutments to limit their centripetal motion, flyweights pivotally mounted on said support having gear segments in engagement with said driven gear and having mutually co-acting abutments to limit their centrip-v etal motion, abutment rings adj-ustably mounted on said support to limit the centrifugal motion of the flyweights, and spring means attached to said rings bearing upon said flyweights to oppose centrifugal force.

10. A speed sensitive mechanical drive com"- prising a driving gear, a driven gear, a rotatable support between said gears, fiyweights of one weight :pivotally mounted on said support having gear segments in engagement with said driving gear and having mutually co-acting abutments to limit their centripetal motion, fiyweights of a different weight pivotally mounted on said support having gear segments in engagement with said driven gear and having mutually co-acting abutments to limit their centripetal motion, abutment rings adjustably mounted on said support to limit the centrifugal motion of the flyweights, and spring means attached to said. rings bearing upon said fiyweights to oppose centrifugal force.

11. A speed sensitive mechanical drive comprising a shaft, a driving gear mounted on said shaft for rotation with respect thereto adapted to receive and to transmit rotary motion from a source of power, a driven gear mounted on said shaft, a support mounted between said gears for rotary motion about said shaft, fiyweights of one Weight pivotally mounted on said support having gear segments in engagement with said driving gear and having mutually co-acting abutments to limit their centripetal motion, flyweights of a different weight pivotally mounted on said support having gear segments in engagement with said driven gear and having mutually co-acting 1;

abutments to limit their centripetal motion, abutment rings adjustably mounted on said support to limit the centrifugal motion of the fly- Weights, and spring means attached to said rings bearing upon said fly-weights to oppose centrifugal force.

12. A speed sensitive mechanical drive comprising a drive shaft, a driving gear mounted on said shaft for rotation with respect thereto adapted to receive and to transmit rotary motion from a source of power, a driven gear mounted on and splined to said shaft, a support mounted between said gears for rotary motion about said shaft, heavy fly-weights pivotally mounted on said support having gear segments in engagement with said driving gear and having mutually co-acting abutments to limit their centripetal motion, light flyweights pivotally-mounted on said support having gear segments in engagement with :said driven gear and having mutually coacting abutments to limit their centripetal motion, abutment rings adjustably mounted on said support to limit the centrifugal motion of the flyweights, and spring means attached to said rings bearing upon said flyweights to oppose centrifugal force.

1.3. Speed sensitive mechanism comprising a shaft, a Weight pivoted eccentrically of said shaft to be rotated therewith and having a surface of material extent concentric with the shaft and a spring bearing on said surface and mounted for bodily movement therealong and independ en'tly of any movement of the weight to vary the leverage of the spring on the weight.

14. Speed sensitive mechanism of the class described comprising a pivoted flyweight operable by centrifugal force, and spring means for controlling said flyweight and movable bodily with respect to and independently of any movement of said flyweight when the latter is in its innermost position to bear upon different parts of the flyWeigh-t at different distances from the pivotal axis thereof when so bodily moved.

ROLLAND M. PURDY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS FOREIGN PATENTS Country Date Great Britain of 1928 France of 1933 Number Number 

